/*
 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 */

package javax.swing;

import java.util.List;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import javax.swing.plaf.*;
import javax.accessibility.*;

import java.awt.Component;
import java.awt.Container;
import java.awt.DefaultFocusTraversalPolicy;
import java.awt.FocusTraversalPolicy;
import java.awt.Window;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.IOException;
import java.beans.PropertyVetoException;
import java.util.Set;
import java.util.TreeSet;
import java.util.LinkedHashSet;

/**
 * A container used to create a multiple-document interface or a virtual desktop. You create
 * <code>JInternalFrame</code> objects and add them to the <code>JDesktopPane</code>.
 * <code>JDesktopPane</code> extends <code>JLayeredPane</code> to manage the potentially overlapping
 * internal frames. It also maintains a reference to an instance of <code>DesktopManager</code> that
 * is set by the UI class for the current look and feel (L&amp;F).  Note that
 * <code>JDesktopPane</code> does not support borders. <p> This class is normally used as the parent
 * of <code>JInternalFrames</code> to provide a pluggable <code>DesktopManager</code> object to the
 * <code>JInternalFrames</code>. The <code>installUI</code> of the L&amp;F specific implementation
 * is responsible for setting the <code>desktopManager</code> variable appropriately. When the
 * parent of a <code>JInternalFrame</code> is a <code>JDesktopPane</code>, it should delegate most
 * of its behavior to the <code>desktopManager</code> (closing, resizing, etc). <p> For further
 * documentation and examples see <a href="https://docs.oracle.com/javase/tutorial/uiswing/components/internalframe.html">How
 * to Use Internal Frames</a>, a section in <em>The Java Tutorial</em>. <p>
 * <strong>Warning:</strong> Swing is not thread safe. For more information see <a
 * href="package-summary.html#threading">Swing's Threading Policy</a>. <p> <strong>Warning:</strong>
 * Serialized objects of this class will not be compatible with future Swing releases. The current
 * serialization support is appropriate for short term storage or RMI between applications running
 * the same version of Swing.  As of 1.4, support for long term storage of all JavaBeans&trade; has
 * been added to the <code>java.beans</code> package. Please see {@link java.beans.XMLEncoder}.
 *
 * @author David Kloba
 * @see JInternalFrame
 * @see JInternalFrame.JDesktopIcon
 * @see DesktopManager
 */
public class JDesktopPane extends JLayeredPane implements Accessible {

  /**
   * @see #getUIClassID
   * @see #readObject
   */
  private static final String uiClassID = "DesktopPaneUI";

  transient DesktopManager desktopManager;

  private transient JInternalFrame selectedFrame = null;

  /**
   * Indicates that the entire contents of the item being dragged
   * should appear inside the desktop pane.
   *
   * @see #OUTLINE_DRAG_MODE
   * @see #setDragMode
   */
  public static final int LIVE_DRAG_MODE = 0;

  /**
   * Indicates that an outline only of the item being dragged
   * should appear inside the desktop pane.
   *
   * @see #LIVE_DRAG_MODE
   * @see #setDragMode
   */
  public static final int OUTLINE_DRAG_MODE = 1;

  private int dragMode = LIVE_DRAG_MODE;
  private boolean dragModeSet = false;
  private transient List<JInternalFrame> framesCache;
  private boolean componentOrderCheckingEnabled = true;
  private boolean componentOrderChanged = false;

  /**
   * Creates a new <code>JDesktopPane</code>.
   */
  public JDesktopPane() {
    setUIProperty("opaque", Boolean.TRUE);
    setFocusCycleRoot(true);

    setFocusTraversalPolicy(new LayoutFocusTraversalPolicy() {
      public Component getDefaultComponent(Container c) {
        JInternalFrame jifArray[] = getAllFrames();
        Component comp = null;
        for (JInternalFrame jif : jifArray) {
          comp = jif.getFocusTraversalPolicy().getDefaultComponent(jif);
          if (comp != null) {
            break;
          }
        }
        return comp;
      }
    });
    updateUI();
  }

  /**
   * Returns the L&amp;F object that renders this component.
   *
   * @return the <code>DesktopPaneUI</code> object that renders this component
   */
  public DesktopPaneUI getUI() {
    return (DesktopPaneUI) ui;
  }

  /**
   * Sets the L&amp;F object that renders this component.
   *
   * @param ui the DesktopPaneUI L&amp;F object
   * @beaninfo bound: true hidden: true attribute: visualUpdate true description: The UI object that
   * implements the Component's LookAndFeel.
   * @see UIDefaults#getUI
   */
  public void setUI(DesktopPaneUI ui) {
    super.setUI(ui);
  }

  /**
   * Sets the "dragging style" used by the desktop pane.
   * You may want to change to one mode or another for
   * performance or aesthetic reasons.
   *
   * @param dragMode the style of drag to use for items in the Desktop
   * @beaninfo bound: true description: Dragging style for internal frame children. enum:
   * LIVE_DRAG_MODE JDesktopPane.LIVE_DRAG_MODE OUTLINE_DRAG_MODE JDesktopPane.OUTLINE_DRAG_MODE
   * @see #LIVE_DRAG_MODE
   * @see #OUTLINE_DRAG_MODE
   * @since 1.3
   */
  public void setDragMode(int dragMode) {
    int oldDragMode = this.dragMode;
    this.dragMode = dragMode;
    firePropertyChange("dragMode", oldDragMode, this.dragMode);
    dragModeSet = true;
  }

  /**
   * Gets the current "dragging style" used by the desktop pane.
   *
   * @return either <code>Live_DRAG_MODE</code> or <code>OUTLINE_DRAG_MODE</code>
   * @see #setDragMode
   * @since 1.3
   */
  public int getDragMode() {
    return dragMode;
  }

  /**
   * Returns the <code>DesktopManger</code> that handles
   * desktop-specific UI actions.
   */
  public DesktopManager getDesktopManager() {
    return desktopManager;
  }

  /**
   * Sets the <code>DesktopManger</code> that will handle
   * desktop-specific UI actions. This may be overridden by
   * {@code LookAndFeel}.
   *
   * @param d the <code>DesktopManager</code> to use
   * @beaninfo bound: true description: Desktop manager to handle the internal frames in the desktop
   * pane.
   */
  public void setDesktopManager(DesktopManager d) {
    DesktopManager oldValue = desktopManager;
    desktopManager = d;
    firePropertyChange("desktopManager", oldValue, desktopManager);
  }

  /**
   * Notification from the <code>UIManager</code> that the L&amp;F has changed.
   * Replaces the current UI object with the latest version from the
   * <code>UIManager</code>.
   *
   * @see JComponent#updateUI
   */
  public void updateUI() {
    setUI((DesktopPaneUI) UIManager.getUI(this));
  }


  /**
   * Returns the name of the L&amp;F class that renders this component.
   *
   * @return the string "DesktopPaneUI"
   * @see JComponent#getUIClassID
   * @see UIDefaults#getUI
   */
  public String getUIClassID() {
    return uiClassID;
  }

  /**
   * Returns all <code>JInternalFrames</code> currently displayed in the
   * desktop. Returns iconified frames as well as expanded frames.
   *
   * @return an array of <code>JInternalFrame</code> objects
   */
  public JInternalFrame[] getAllFrames() {
    return getAllFrames(this).toArray(new JInternalFrame[0]);
  }

  private static Collection<JInternalFrame> getAllFrames(Container parent) {
    int i, count;
    Collection<JInternalFrame> results = new LinkedHashSet<>();
    count = parent.getComponentCount();
    for (i = 0; i < count; i++) {
      Component next = parent.getComponent(i);
      if (next instanceof JInternalFrame) {
        results.add((JInternalFrame) next);
      } else if (next instanceof JInternalFrame.JDesktopIcon) {
        JInternalFrame tmp = ((JInternalFrame.JDesktopIcon) next).getInternalFrame();
        if (tmp != null) {
          results.add(tmp);
        }
      } else if (next instanceof Container) {
        results.addAll(getAllFrames((Container) next));
      }
    }
    return results;
  }

  /**
   * Returns the currently active <code>JInternalFrame</code>
   * in this <code>JDesktopPane</code>, or <code>null</code>
   * if no <code>JInternalFrame</code> is currently active.
   *
   * @return the currently active <code>JInternalFrame</code> or <code>null</code>
   * @since 1.3
   */

  public JInternalFrame getSelectedFrame() {
    return selectedFrame;
  }

  /**
   * Sets the currently active <code>JInternalFrame</code>
   * in this <code>JDesktopPane</code>. This method is used to bridge
   * the package gap between JDesktopPane and the platform implementation
   * code and should not be called directly. To visually select the frame
   * the client must call JInternalFrame.setSelected(true) to activate
   * the frame.
   *
   * @param f the internal frame that's currently selected
   * @see JInternalFrame#setSelected(boolean)
   * @since 1.3
   */

  public void setSelectedFrame(JInternalFrame f) {
    selectedFrame = f;
  }

  /**
   * Returns all <code>JInternalFrames</code> currently displayed in the
   * specified layer of the desktop. Returns iconified frames as well
   * expanded frames.
   *
   * @param layer an int specifying the desktop layer
   * @return an array of <code>JInternalFrame</code> objects
   * @see JLayeredPane
   */
  public JInternalFrame[] getAllFramesInLayer(int layer) {
    Collection<JInternalFrame> allFrames = getAllFrames(this);
    Iterator<JInternalFrame> iterator = allFrames.iterator();
    while (iterator.hasNext()) {
      if (iterator.next().getLayer() != layer) {
        iterator.remove();
      }
    }
    return allFrames.toArray(new JInternalFrame[0]);
  }

  private List<JInternalFrame> getFrames() {
    Component c;
    Set<ComponentPosition> set = new TreeSet<ComponentPosition>();
    for (int i = 0; i < getComponentCount(); i++) {
      c = getComponent(i);
      if (c instanceof JInternalFrame) {
        set.add(new ComponentPosition((JInternalFrame) c, getLayer(c),
            i));
      } else if (c instanceof JInternalFrame.JDesktopIcon) {
        c = ((JInternalFrame.JDesktopIcon) c).getInternalFrame();
        set.add(new ComponentPosition((JInternalFrame) c, getLayer(c),
            i));
      }
    }
    List<JInternalFrame> frames = new ArrayList<JInternalFrame>(
        set.size());
    for (ComponentPosition position : set) {
      frames.add(position.component);
    }
    return frames;
  }

  private static class ComponentPosition implements
      Comparable<ComponentPosition> {

    private final JInternalFrame component;
    private final int layer;
    private final int zOrder;

    ComponentPosition(JInternalFrame component, int layer, int zOrder) {
      this.component = component;
      this.layer = layer;
      this.zOrder = zOrder;
    }

    public int compareTo(ComponentPosition o) {
      int delta = o.layer - layer;
      if (delta == 0) {
        return zOrder - o.zOrder;
      }
      return delta;
    }
  }

  private JInternalFrame getNextFrame(JInternalFrame f, boolean forward) {
    verifyFramesCache();
    if (f == null) {
      return getTopInternalFrame();
    }
    int i = framesCache.indexOf(f);
    if (i == -1 || framesCache.size() == 1) {
            /* error */
      return null;
    }
    if (forward) {
      // navigate to the next frame
      if (++i == framesCache.size()) {
                /* wrap */
        i = 0;
      }
    } else {
      // navigate to the previous frame
      if (--i == -1) {
                /* wrap */
        i = framesCache.size() - 1;
      }
    }
    return framesCache.get(i);
  }

  JInternalFrame getNextFrame(JInternalFrame f) {
    return getNextFrame(f, true);
  }

  private JInternalFrame getTopInternalFrame() {
    if (framesCache.size() == 0) {
      return null;
    }
    return framesCache.get(0);
  }

  private void updateFramesCache() {
    framesCache = getFrames();
  }

  private void verifyFramesCache() {
    // If framesCache is dirty, then recreate it.
    if (componentOrderChanged) {
      componentOrderChanged = false;
      updateFramesCache();
    }
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public void remove(Component comp) {
    super.remove(comp);
    updateFramesCache();
  }

  /**
   * Selects the next <code>JInternalFrame</code> in this desktop pane.
   *
   * @param forward a boolean indicating which direction to select in; <code>true</code> for
   * forward, <code>false</code> for backward
   * @return the JInternalFrame that was selected or <code>null</code> if nothing was selected
   * @since 1.6
   */
  public JInternalFrame selectFrame(boolean forward) {
    JInternalFrame selectedFrame = getSelectedFrame();
    JInternalFrame frameToSelect = getNextFrame(selectedFrame, forward);
    if (frameToSelect == null) {
      return null;
    }
    // Maintain navigation traversal order until an
    // external stack change, such as a click on a frame.
    setComponentOrderCheckingEnabled(false);
    if (forward && selectedFrame != null) {
      selectedFrame.moveToBack();  // For Windows MDI fidelity.
    }
    try {
      frameToSelect.setSelected(true);
    } catch (PropertyVetoException pve) {
    }
    setComponentOrderCheckingEnabled(true);
    return frameToSelect;
  }

  /*
   * Sets whether component order checking is enabled.
   * @param enable a boolean value, where <code>true</code> means
   * a change in component order will cause a change in the keyboard
   * navigation order.
   * @since 1.6
   */
  void setComponentOrderCheckingEnabled(boolean enable) {
    componentOrderCheckingEnabled = enable;
  }

  /**
   * {@inheritDoc}
   *
   * @since 1.6
   */
  protected void addImpl(Component comp, Object constraints, int index) {
    super.addImpl(comp, constraints, index);
    if (componentOrderCheckingEnabled) {
      if (comp instanceof JInternalFrame ||
          comp instanceof JInternalFrame.JDesktopIcon) {
        componentOrderChanged = true;
      }
    }
  }

  /**
   * {@inheritDoc}
   *
   * @since 1.6
   */
  public void remove(int index) {
    if (componentOrderCheckingEnabled) {
      Component comp = getComponent(index);
      if (comp instanceof JInternalFrame ||
          comp instanceof JInternalFrame.JDesktopIcon) {
        componentOrderChanged = true;
      }
    }
    super.remove(index);
  }

  /**
   * {@inheritDoc}
   *
   * @since 1.6
   */
  public void removeAll() {
    if (componentOrderCheckingEnabled) {
      int count = getComponentCount();
      for (int i = 0; i < count; i++) {
        Component comp = getComponent(i);
        if (comp instanceof JInternalFrame ||
            comp instanceof JInternalFrame.JDesktopIcon) {
          componentOrderChanged = true;
          break;
        }
      }
    }
    super.removeAll();
  }

  /**
   * {@inheritDoc}
   *
   * @since 1.6
   */
  public void setComponentZOrder(Component comp, int index) {
    super.setComponentZOrder(comp, index);
    if (componentOrderCheckingEnabled) {
      if (comp instanceof JInternalFrame ||
          comp instanceof JInternalFrame.JDesktopIcon) {
        componentOrderChanged = true;
      }
    }
  }

  /**
   * See readObject() and writeObject() in JComponent for more
   * information about serialization in Swing.
   */
  private void writeObject(ObjectOutputStream s) throws IOException {
    s.defaultWriteObject();
    if (getUIClassID().equals(uiClassID)) {
      byte count = JComponent.getWriteObjCounter(this);
      JComponent.setWriteObjCounter(this, --count);
      if (count == 0 && ui != null) {
        ui.installUI(this);
      }
    }
  }

  void setUIProperty(String propertyName, Object value) {
    if (propertyName == "dragMode") {
      if (!dragModeSet) {
        setDragMode(((Integer) value).intValue());
        dragModeSet = false;
      }
    } else {
      super.setUIProperty(propertyName, value);
    }
  }

  /**
   * Returns a string representation of this <code>JDesktopPane</code>.
   * This method is intended to be used only for debugging purposes, and the
   * content and format of the returned string may vary between
   * implementations. The returned string may be empty but may not
   * be <code>null</code>.
   *
   * @return a string representation of this <code>JDesktopPane</code>
   */
  protected String paramString() {
    String desktopManagerString = (desktopManager != null ?
        desktopManager.toString() : "");

    return super.paramString() +
        ",desktopManager=" + desktopManagerString;
  }

/////////////////
// Accessibility support
////////////////

  /**
   * Gets the <code>AccessibleContext</code> associated with this
   * <code>JDesktopPane</code>. For desktop panes, the
   * <code>AccessibleContext</code> takes the form of an
   * <code>AccessibleJDesktopPane</code>.
   * A new <code>AccessibleJDesktopPane</code> instance is created if necessary.
   *
   * @return an <code>AccessibleJDesktopPane</code> that serves as the <code>AccessibleContext</code>
   * of this <code>JDesktopPane</code>
   */
  public AccessibleContext getAccessibleContext() {
    if (accessibleContext == null) {
      accessibleContext = new AccessibleJDesktopPane();
    }
    return accessibleContext;
  }

  /**
   * This class implements accessibility support for the
   * <code>JDesktopPane</code> class.  It provides an implementation of the
   * Java Accessibility API appropriate to desktop pane user-interface
   * elements.
   * <p>
   * <strong>Warning:</strong>
   * Serialized objects of this class will not be compatible with
   * future Swing releases. The current serialization support is
   * appropriate for short term storage or RMI between applications running
   * the same version of Swing.  As of 1.4, support for long term storage
   * of all JavaBeans&trade;
   * has been added to the <code>java.beans</code> package.
   * Please see {@link java.beans.XMLEncoder}.
   */
  protected class AccessibleJDesktopPane extends AccessibleJComponent {

    /**
     * Get the role of this object.
     *
     * @return an instance of AccessibleRole describing the role of the object
     * @see AccessibleRole
     */
    public AccessibleRole getAccessibleRole() {
      return AccessibleRole.DESKTOP_PANE;
    }
  }
}
